A new model equation for determining the measurement result in standard addition experiments was derived and successfully applied to the quantitative determination of rhodium in automotive catalysts. Existing equations for standard addition experiments with gravimetric preparation were changed in order to integrate the novel idea of including the uncertainty associated with the standard into the model equation. Using this novel equation combined with the ordinary least squares algorithm for the regression line also yielded a new formula for the associated measurement uncertainty. This uncertainty accounts for the first time for the uncertainty associated with the standard. The derivation for the model equation and the resulting associated measurement uncertainty is shown for gravimetric standard addition experiments both with and without an internal standard.

The aim of this comparison was to demonstrate the capability of national metrology institutes to measure elemental mass fractions at a level of w(E) ≈ 1 g/kg as found in almost all mono-elemental calibration solutions. These calibration solutions represent an important link in traceability systems in inorganic analysis. Virtually all traceable routine measurements are linked to the SI through these calibration solutions. Every participant was provided with three solutions of each of the three selected elements chromium, cobalt and lead. This comparison was a joint activity of the Inorganic Analysis Working Group (IAWG) and the Electrochemical Analysis Working Group (EAWG) of the CCQM and was piloted by the Physikalisch-Technische Bundesanstalt (PTB, Braunschweig, Germany) with the help of the Bundesanstalt für Materialforschung und -prüfung (BAM, Berlin, Germany), the Centro Nacional de Metrología (CENAM, Querétaro, Mexico) and the National Institute of Standards and Technology (NIST, Gaithersburg, USA).A small majority of participants applied inductively coupled plasma optical emission spectrometry (ICP OES) in combination with a variety of calibration strategies (one-point-calibration, bracketing, calibration curve, each with and without an internal standard). But also IDMS techniques were carried out on quadrupole, high resolution and multicollector ICP-MS machines as well as a TIMS machine. Several participants applied titrimetry. FAAS as well as ICP-MS combined with non-IDMS calibration strategies were used by at least one participant. The key comparison reference values (KCRV) were agreed upon during the IAWG/EAWG meeting in November 2011 held in Sydney as the added element content calculated from the gravimetric sample preparation. Accordingly the degrees of equivalence were calculated. Despite the large variety of methods applied no superior method could be identified. The relative deviation of the median of the participants' results from the gravimetric reference value was equal or smaller than 0.1% (with an average of 0.05%) in the case of all three elements.Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Two reference measurement procedures are presented here that allow the determination of the iron saturation in human transferrin, based on different molecular properties. The results, directly derived from the number of ions bound to the protein molecule, are traceable to the SI. Up to now, the iron saturation has only been deduced indirectly from the amount-of-substance ratio of serum iron to transferrin in serum. Interlaboratory tests have shown the need for more accurate methods, as the results from many participant test samples for both parameters do not lie within the acceptable range of deviation given by relevant guidelines when different methods or kits are applied. Using isotope dilution, an HPLC ICP-MS procedure was developed in compliance with the requirements of a primary reference measurement procedure. In this manner, the iron saturation was measured with an associated relative expanded measurement uncertainty of 4%. Based on the results, a straightforward Raman procedure was evolved, which allows the determination of the iron saturation in transferrin with an associated relative expanded uncertainty of 7%.

/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. Questions? Contact the NRC Publications Archive team atPublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information. NRC Publications Archive Archives des publications du CNRCFor the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://doi.org/10.1088/0026-1394/51/1A/08008 Metrologia, 51, 1A, 2014-01-01 CCQM-K72 Purity of Zinc with respect to six defined metallic analytes MotivationHigh purity elements can serve as a realisation of the SI unit amount of substance for the specific element. Solutions prepared from high purity metals by applying gravimetric preparation and the concept of molar mass are used as 'calibration' solutions in many fields of analytical chemistry and provide the metrological basis in elemental analysis. Since ideal purity does not exist for real materials, the actual purity of the high purity material must be known with a specified uncertainty. Such purity data, however, are only accessible via measurements, which are limited by their measurement uncertainty. Aiming at uncertainties around 10 -4relative on the purity statement in almost all cases a direct measurement of the element in itself is not applicable, because the available methods are not sufficiently selective and/or accurate. Therefore the indirect approach is followed in order to achieve uncertainties at this level. In the indirect approach the mass fractions of all impurities, in other words all elements excepting the matrix element, are measured and their sum is subtracted from the value for ideal purity, which is 1 kg/kg. Uncertainties at the 10 -4 level are aimed at because high purity metals are not only destined for being used as convenient primary realisations of the SI unit, but also as primary assays or so-called back-spikes in double isotope dilution mass spectrometry (IDMS). With double IDMS combined uncertainties down to 5·10 -4 can be achieved and therefore the uncertainty on the purity statement for these materials should be at or even lower than 10 -4 relative in order not to compromise the IDMS results.As a first step, only six metallic impurities are considered in previous studies and also in this comparison, in order to limit the effort within this study. Other metallic and non-metallic impurities might be subject to future CCQM studies. Zinc was chosen as matrix, due to its ease of...

READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE. https://nrc-publications.canada.ca/eng/copyright Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à